Common mental illnesses, such as depression, are an important public health concern. According to projections by the World Health Organisation, depressive disorders will be the leading cause of disease burden in high-income countries by 2030. In addition to human misery, mental illnesses often result in substantial work impairment and lost work days. Closer to home, according to the Mental Health Commission of Canada, mental illnesses and mental health issues are the leading cause of short- and long-term disability in Canada. The cost of dealing with these issues is in the range of $51 billion per year, with almost $20 billion of that amount coming from workplace losses.

What the study tells us

The study was funded by the British Medical Research Council, British Heart Foundation, Stroke Association, United States National Heart Lung and Blood Institute and the US National Institute on Aging. Several authors participated, led by Dr. Marianna Virtanen of the Finnish Institute of Occupational Health and University College London.

The study followed 2,123 middle-aged civil servants for six years. Most of the civil servants, 52 percent, worked a regular workday. Another 37 percent averaged 9- or 10-hour days and 11 percent clocked 11 hours or more. All of the subjects were considered mentally healthy when they started the study. After six years, just over three percent were diagnosed with clinical depression. Those who worked an average of at least 11 hours a day showed up to 2.5 times the risk of a major depressive episode compared with those working a standard seven- to eight-hour day, the researchers found.

“Although occasionally working overtime may have benefits for the individual and society, it is important to recognize that working excessive hours is also associated with an increased risk of major depression,” says Dr. Virtanen.

Although they do not yield exactly the same results, several other ongoing studies in various countries concur, suggesting that long working hours may increase the risk of various adverse outcomes, including psychological distress and symptoms of depression and anxiety, decline in cognitive function and new-onset sleep disturbances. However, others have yielded a completely opposite point of view.

For example, in a follow-up of Canadians over 1–2 years, working 41 hours or more per week compared to 35–40 hours was associated with a higher rate of new-onset major depressive episode among women but not among men. Another study with a 24-year follow-up did not find any association between “overtime work” and incidence of depressive disorder, including cases of subclinical depression.

It is important to note that as all civil servants are white-collar workers, it remains to be seen whether the recent findings can be applied to blue-collar workers and employees in the private sector. There is a need and a call for additional studies, including research to examine whether interventions designed to reduce working hours would alter depression risk in working populations.

In addition, plausible explanations of why long working hours are associated with the development of depression cannot be drawn directly from the study. There are too many outside factors such as work-family conflicts, difficulties in unwinding after work, or prolonged increased cortisol levels (level of the hormone cortisol in the blood). The effect of long working hours on mental health may also be different in women and men. To date, the exact cause of depression is not known, but it is widely assumed that it is multifactorial involving genetic, biological and psychosocial factors.

The study examined the effects of changes in job control (the ability to make decisions and use skills at work), psychological demands (the pace and mental intensity of work) and social support on subsequent depression. Using the National Population Health Survey, researchers looked for these effects among 3,735 Canadians who were ages 25 to 60 in 2000–01, and who worked at some point in both 2000–01 and 2002–03. One key finding: increases in psychological demands are more important than declines in job control for the onset of depression in Canadian workers.

What can employers take from these studies?

Work-related depression, mental illness and stress arises where work demands of various types and combinations (e.g., overtime, heavy workload) exceed the person’s capacity and capability to cope. For example, a person might feel under pressure if the demands of their job (such as hours or responsibilities) are greater than they can comfortably manage. Other sources of work-related stress or mental illness include conflict with co-workers or bosses, constant change and threats to job security, such as potential redundancy.

It is important to note that employees are not all the same. What one person may perceive as stressful, however, another may view as challenging. It will all depend on their job, their physical and emotional make-up, their health, personal life and other factors. Also, what may be challenging at one point may become stressful when certain factors change or time elapses.

It is important for employers to recognize work-related stress and mental illnesses such as depression as a significant health and safety issue. A company can and should take steps to ensure that employees are not subjected to unnecessary stress at work.

Employers should think of cutting down on the need for overtime by reorganizing duties or employing extra staff. Encourage an environment where employees have more say over their duties, promotional prospects and safety. Take into account the personal lives of employees and recognize that the demands of home will sometimes clash with the demands of work, and make sure that everyone is properly trained for their job, among other measures. Also, employers should not stigmatize the issue of mental illness, but invite employees to openly discuss the issue by implementing a stress management program where all employees can participate.

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Yosie Saint-Cyr, LL.B., is a trained lawyer called to the Quebec bar in 1988 and is still a member in good standing. She practiced business, employment and labour law until 1999. For over 18 years, Yosie has been the Managing Editor of the following publications, Human Resources Advisor, Human Resources PolicyPro, HRinfodesk and Accessibility Standards PolicyPro from First Reference. Yosie is one of Canada’s best known and most respected HR authors, with an extensive background in employment and labour across the country. Read more

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